From: Raymond Law <rayvinly@...>
Date: 2007-03-23T00:06:31+09:00
Subject: SVG::Graph::Plot

I encountered a problem when using SVG::Graph.  I have the following
code that generate a simple plot:

require 'SVG/Graph/Plot'

# This does not work.
data= [0.107,9, 0.128,1, 0.163,2, 0.188,4, 0.192,6, 0.5,5.5]

# This works fine.
#data= [0.107,9, 0.128,1, 0.163,2, 0.188,4, 0.192,6, 1.5,5.5]

graph = SVG::Graph::Plot.new({
  :height => 500,
  :width => 800,
  :key => true,
  :scale_x_integers => true,
  :scale_y_integerrs => true,
})

graph.add_data({
  :data => data,
  :title => 'Projected'
})

f = File.new("plot.svg", "w+")
f.write(graph.burn())
f.close

The error is:

123 rlaw ~/svg_graph/test > ruby plot.rb
/usr/local/lib/ruby/site_ruby/1.8/SVG/Graph/Plot.rb:206:in `-': nil
can't be coerced into Float (TypeError)
        from /usr/local/lib/ruby/site_ruby/1.8/SVG/Graph/Plot.rb:206:in
`field_width'
        from /usr/local/lib/ruby/site_ruby/1.8/SVG/Graph/Graph.rb:522:in
`draw_x_labels'
        from /usr/local/lib/ruby/site_ruby/1.8/SVG/Graph/Graph.rb:488:in
`draw_graph'
        from /usr/local/lib/ruby/site_ruby/1.8/SVG/Graph/Graph.rb:203:in
`burn'
        from plot.rb:19
124 rlaw ~/svg_graph/test >

Basically, when x's are very small (i.e. smaller than 1?), I get the
above error.  Is this a known bug, or am I just not using it right?

Thank you.

Ray,

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